MBMS is a point-to-multipoint service in which data is transmitted from a single source entity to multiple recipients, as described in 3GPP TS 23.246 (v12.4.0). Transmitting the same data to multiple recipients allows network resources to be shared in the radio access network and/or the core network. MBMS offers two modes: broadcast mode and multicast mode. In broadcast mode, a source entity uses network resources to transmit content within a service area that is received by all mobile devices in the service area. In multicast mode, a source entity uses network resources to transmit content to specific mobile devices within a service area.
A Broadcast Multicast Service Center (BM-SC) is an entity that provides functions for MBMS user service provisioning and delivery. The BM-SC may serve as an entry point for content provider MBMS transmissions, may authorize and initiate MBMS bearer services, and may schedule and deliver MBMS transmissions. To charge for MBMS transmission, the BM-SC includes a Charging Trigger Function (CTF) that provides charging information to an offline charging system (OFCS).
The 3GPP has also defined a Group Communication Service (GCS) to transmit application signaling and data to members of a group, as described in 3GPP TS 23.268 (v12.3.0). For example, a source entity may define a group of twenty members, and the source entity may use the GCS to send content to the members of the group. GCS may use Evolved Packet System (EPS) bearer services or MBMS bearer services to deliver the application signaling and/or data to the members of the group. However, the 3GPP has not adequately described how to charge for group communications that utilize MBMS bearer services.